Like old movie posters or photo in film magazine, which were printed from 35mm films of the very moment of frames in that particular movie.
I have done with my gh3 video, which is just like the 1D C ad claimed, you will get more chance to get a decent shot of your objects with video than with photo only. A video portrait of human or animal for example are way easier than shooting only with photo function. Try to look at your video portrait of person (wedding are a good example, but my experience was with a violinist ), change in between frames on your computer you will find much more picture you liked for a photo purpose. Of course there are some will be blur because most of them are 1/50 shot. But overall it can be very good.
I printed some 1080P frames with canon Pixma pro 100 from MAC OS print screen function. They were great. So in this regard, GH4 4K video can serve for this purpose well since it will be 8M vs 2M pixels.